1. Field of the Disclosure
Embodiments disclosed herein relate generally to a process for the alkylation or transalkylation of aromatic compounds with olefins, alcohols and/or alkyl halides. In another aspect, embodiments disclosed herein relate to a process for the production of catalysts useful for the alkylation or transalkylation of aromatic compounds.
2. Background
Alkylation refers generally to a type of chemical reaction resulting in addition of an alkyl group to an organic compound. Olefins, such as ethylene, propylene, and butylenes, are well-known alkylating agents, frequently used in synthesis of alkylated derivatives. Alkylation of benzene is a commercially important process, used to increase the octane rating of fuel and to produce valuable chemical feedstocks. For example, alkylation of benzene with ethylene may be used to produce ethylbenzene, which may be subsequently converted to styrene. Similarly, alkylation of benzene with propylene may be used to produce cumene, which may be subsequently converted to phenol and acetone.
A typical benzene alkylation reaction is shown below:

Alkylation technology, still widely employed in the petrochemical industry, involves the use of a catalyst based on phosphoric acid. Newer technology utilizes non-polluting, non-corrosive, regenerable materials, such as zeolitic molecular sieve catalysts. U.S. Pat. Nos. 4,371,714 and 4,469,908 disclose straight pass alkylation of aromatic compounds using molecular sieve catalysts in fixed beds. However, there are two main problems arising from the use of zeolitic catalysts in alkylation reactions, namely a rapid deactivation of the zeolitic catalyst due to coking and poisoning and a higher yield of polyalkylated by-products. Other patents discussing use of zeolitic catalysts for alkylation and transalkylation may include U.S. Pat. Nos. 5,118,897, 4,083,886, and 4,891,458, among others.
Zeolitic materials, both natural and synthetic, have been demonstrated to have catalytic properties for various types of hydrocarbon conversion, including alkylation as mentioned above. It is often advantageous to dealuminate these materials in order to improve their process performance. Performance measures typically improved following dealumination include product selectivity, product quality and catalyst stability.
Conventional techniques for zeolite dealumination include hydrothermal treatment, mineral acid treatment with HCl, HNO3, and H2SO4, and chemical treatment with SiCl4 or ethylenediaminetetraacetic acid (EDTA). The treatments are limited, in many cases, in the extent of dealumination by the onset of crystal degradation and loss of sorption capacity. U.S. Pat. No. 4,419,220 discloses that dealumination of zeolite Beta via treatment with HCl solutions is limited to SiO2/Al2O3 ratios of about 200 to 300 beyond which significant losses to zeolite crystallinity are observed.
U.S. Pat. No. 3,442,795 describes a process for preparing highly siliceous zeolite-type materials from crystalline aluminosilicates by means of a solvolysis, e.g. hydrolysis, followed by a chelation. In this process, the acid form of a zeolite is subjected to hydrolysis, to remove aluminum from the aluminosilicate. The aluminum can then be physically separated from the aluminosilicate by the use of complexing or chelating agents such as ethylenediaminetetraacetic acid or carboxylic acid, to form aluminum complexes that are readily removable from the aluminosilicate. The examples are directed to the use of EDTA to remove alumina.
EP 0 259 526 B1 discloses the use of dealumination in producing ECR-17. The preferred dealumination method involves a combination of steam treatment and acid leaching, or chemical treatments with silicon halides. The acid used is preferably a mineral acid, such as HCl, HNO3 or H2SO4, but may also be weaker acids such as formic, acetic, citric, oxalic, tartaric acids and the like.
U.S. Pat. No. 5,310,534 discloses the dealumination of zeolites using strong inorganic and organic acids, such as formic acid, trichloroacetic acid, trifluoracetic acid, hydrochloric acid, sulfuric acid, and nitric acid.
U.S. Pat. No. 5,874,647 discloses a process for preparing a zeolite catalyst including hydrothermally treating a catalyst with a gas including water and inert components at an elevated temperature followed by treating of the catalyst with an acid, such as nitric, oxalic, hydrochloric, methanesulfonic, fluorosulfonic, and hydrofluoric acid.
U.S. Pat. No. 6,620,402 discloses a process including the dealumination of zeolites by removal of the zeolite framework or crystal structure, such as obtained by removal of the Al+3 ions. Dealuminizing agents include mineral acids, polyvalent acids, and chelating agents, such as an ammonium-containing agent.
Other various patents describing aluminum extraction from a zeolite may include U.S. Pat. Nos. 4,954,243, 5,242,676, 5,200,168, 5,304,695, 5,567,666, 5,929,295, 6,025,293, 5,723,710, and 5,321,194.
Conditions used in many prior art dealumination processes may result in loss of high acidity framework aluminum sites within the catalyst, which additionally results in a loss of catalyst activity. Accordingly, there exists a need for dealumination processes that may selectively remove only a portion of the alumina, non-framework aluminum, enhancing the accessibility to the strong acidic sites contained in the zeolitic structure.